Transcript Case Study

Case Study 46
Julia Kofler, M.D.
Question 1
Clinical history:
29-year-old man who presented with a history of near
syncopal episode, headache and mild ataxia.
Describe the lesion on the following MRI scan.
Question 1
T1
T1 with contrast
Answer
Minimally contrast-enhancing fourth ventricular mass.
Question 2
What is your differential diagnosis based on the radiologic
appearance and location of the lesion?
Answer
 Subependymoma
 Ependymoma
 Choroid plexus tumor
 Pilocytic astrocytoma
 Meningioma
 Medulloblastoma
Question 3
Which of the tumors in your differential is least likely to be
contrast-enhancing?
Answer
Subependymoma
Question 4
A resection of the tumor was performed. Describe the
findings on the permanent section.
Click here to view slide.
Answer
 Clusters of tumor nuclei in a densely fibrillar
background with large anuclear areas
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Mildly pleomorphic nuclei with inconspicuous nucleoli
Variable microcystic changes
Rare calcifications
Hyalinized vessels
Focal intratumoral hemorrhage
No mitoses are seen
Question 5
What is your diagnosis?
Answer
Subependymoma
Question 6
Subependymomas correspond to which WHO grade?
Answer
WHO grade 1
Question 7
Some differences with regard to dominant histologic
features have been described for supratentorial and fourth
ventricular subependymomas. Name some of these
features.
Answer
 Supratentorial subependymomas are more prone to
microcystic change and are usually not calcified
 Fourth ventricular subependymomas are commonly
calcified and often lack microcystic change
Question 8
Some subependymomas contain a component of
ependymoma and are classified as mixed
subependymoma/ependymoma.
How common are these mixed tumors?
Answer
About 5-20% of subependymomas have an
ependymomatous component
Question 9
What is the prognostic significance of the
ependymomatous component in mixed tumors?
Answer
Mixed tumors are graded based on the ependymoma
component as WHO grade II or III neoplasms
Question 10
What is the immunohistochemical profile of
subependymomas?
Answer
 GFAP positive
 S100 positive
 Vimentin positive
 Variable reactivity for neuronal markers of low
specificity (NCAM, NSE)
 Ki-67 labeling index usually <1%